In recent years, a magnetic random access memory (MRAM) has become a topic of interest. In the MRAM of the related art, for example, a method as described in U.S. Pat. No. 5,734,605 performs recording by reversing magnetization at one side of a tunnel magneto-resistive effect (TMR) element having a multi-layer structure of magnetic film/non-magnetic insulating film/magnetic film by using a combined magnetic field that is generated due to current flowing in two metal lines disposed in an orthogonal direction to each other at an upper and lower of the TMR element.
However, in the MRAM, if a size of the TMR element becomes small so as to make its capacity large, a magnitude of a magnetic field required for reversing magnetization should be large. For this reason, there is a need to flow a large amount of current in the metal lines of the MRAM. As a result, there is a problem in that power consumption increases and the metal lines become damaged.
As a method of performing magnetization reversal without using a magnetic field, there is, for example, a “Journal of Magnetism and Magnetic Materials, 159, L1-6 (1996)” that can achieve the magnetization reversal by flowing a predetermined or more current in a giant magneto-resistive effect (GMR) film or a tunnel magneto-resistive effect (TMR) film that are used in a magnetic reproducing head.
Thereafter, “Physical Review Letters, Vol. 84, No. 14, pp. 3149-3152 (2000)” and “Applied Physics Letters, Vol. 77, 23, pp. 3809-3811” disclose an experimental example of a recording method that reverses magnetization of a Co layer by forming a pillar having a diameter of 130 nm including a multi-layer film (GMR film) of Co/Cu/Co between two electrodes of Cu, flowing current in the pillar, and using the spin torque provided to the magnetization of the Co layer by spinning the flowing current.
In recent years, “Applied Physics Letters, Vol. 84, pp. 3118-3120 (2004)” discloses an actual proof the spin torque magnetization reversal is possible by using a nano pillar that uses the TMR film. In particular, reversing the spin torque magnetization using the TMR film can obtain an output that is equal to or more than the MRAM of the related art, such that this has become an interested topic.